Fuente: Contactar Dhand, MD, médico, medicina interna, Beth Israel Deaconess Medical Center de asistir
Competencia en el uso de un estetoscopio para escuchar sonidos de corazón y la capacidad de diferenciar entre ruidos cardíacos normales y anormales son habilidades esenciales para cualquier médico. Colocación correcta del estetoscopio en el pecho se corresponde con el sonido de las válvulas cardiacas que se cierre. El corazón tiene dos sonidos principales: S1 y S2. El primer sonido de corazón (S1) se produce como la válvula mitral y tricúspide (válvulas auriculoventriculares) cierre después de sangre entra en los ventrículos. Esto representa el comienzo de la sístole. El segundo sonido de corazón (S2) se produce cuando se cierran las válvulas aórticas y pulmonares (válvulas semilunares) después de sangre ha dejado a los ventrículos para entrar en los sistemas de circulación sistémica y pulmonar al final de la sístole. Tradicionalmente, los sonidos se conocen como un “lub-dub”.
Auscultación del corazón se realiza con diafragma y campana de partes de la pieza de pecho de estetoscopio. El diafragma es más comúnmente utilizado y es el mejor para sonidos de alta frecuencia (como S1 y S2) y soplos de regurgitación mitral y estenosis aórtica. El diafragma debe presionarse firmemente contra la pared de pecho. La campana mejor transmite sonidos de baja frecuencia (por ejemplo, S3 y S4) y el soplo de la estenosis mitral. La campana debe aplicarse con una ligera presión.
Auscultation of the heart remains one of the fundamental skills for any clinician to master, and it provides vital diagnostic clues to many cardiac abnormalities. Learning the correct technique for auscultation is essential in order to distinguish the normal from the pathological. All cardiac areas must be auscultated in a structured and methodical fashion. The physical findings should be interpreted with respect to the cardiac cycle, and the intensity, duration, pitch, and timing of each sound should be noted. It is essential to memorize the anatomical landmarks where the stethoscope should be placed on the patient's chest, and always examine the patient in a quiet environment. It is important to listen for at least 5 sec, while the patient is breathing normally, to avoid one of the common mistakes made during the physical exam – not allowing adequate time to listen to the heart sounds. Physicians must be familiar with their stethoscopes and engage both the diaphragm and the bell during the heart auscultation.
Proficiency in the use of a stethoscope to listen to heart sounds and the ability to differentiate between normal and abnormal heart sounds are essential skills for any physician.
The heart has two main sounds, S1 and S2. The first sound – S1- occurs as the mitral and tricuspid valves close, after blood enters the ventricles. This represents the start of a systole. The second heart sound – S2 – occurs when the aortic and pulmonary valves close, after blood has left the ventricles to enter the systemic and pulmonary circulation systems at the end of a systole. Together, they sound as “lub-dub”… “lub-dub”.
In this video, we’ll first review the surface landmarks for auscultation, and then we’ll go through the essential steps for this exam. The discussion related to the abnormal heart sounds such as murmurs and gallops will be covered in a separate video of this collection.
Let’s begin by reviewing the surface landmarks for auscultation. As discussed,
The aortic area corresponding to the aortic valve is along right sternal edge of the 2nd intercostal space, abbreviated as the 2nd ICS. Similarly, at the left sternal edge of the same ICS is the pulmonic area associated with the pulmonic valve. Travelling down the left sternal edge, in the 4th or 5th ICS is the tricuspid area corresponding to the tricuspid valve. And in the 5th ICS along the mid-clavicular line is the mitral area linked to the mitral valve.
Now that you’re familiar with the landmarks, let’s review the sequence of steps for this exam. Before starting the procedure wash your hands thoroughly and make sure that the stethoscope has been cleaned with a disinfectant wipe.
First, familiarize yourself with the stethoscope chest piece. The auscultation of the heart is performed using both – the diaphragm and the bell. The diaphragm is best for high frequency sounds, such as S1 and S2. The bell best transmits low frequency sounds, such as S3 and S4.
Begin by ensuring that the area to be examined is exposed, and request the patient to lie down at a 30-45° degree angle on the exam table. Before placing the stethoscope, a good rule of thumb is to locate the 2nd ICS by palpating for the Angle of Louis, which is at the level of the 2nd ICS. Next, place the diaphragm at the right sternal edge of this ICS, which is the aortic area. Listen at each auscultation spot for at least 5 seconds to ensure that you’re not missing any subtle sounds. In addition, throughout the exam ask the patient to breathe in and out, because in presence of an abnormal sound, the timing in the respiratory cycle can provide a vital diagnostic clue. While auscultating the aortic area, listen for S2, which represents the aortic valve closing. Next, move to the pulmonic area, which is on the left sternal edge of the 2nd ICS. Here, again you can clearly distinguish the second heart sound, which represents the pulmonic valve closure. Subsequently, using the diaphragm, auscultate the tricuspid area at the 4th or 5th ICS on the left sternal edge. Here, listen for the first heart sound due to the tricuspid valve closing. Lastly, place the diaphragm in the mitral area and listen for S1, which represents the mitral valve closure.
In addition to the four valve-associated landmarks, auscultation of the lungs and major arteries can provide essential information regarding the cardiovascular functioning. Using the diaphragm, auscultate at the base of the lungs to listen for any crepitations or crackles, which indicate pulmonary edema, a sign of heart failure. Next, with the bell, auscultate the carotid arteries. Frequently, a murmur that is present from the aortic valve may be heard in this area. Also, auscultate here for a bruit, which is a swishing sound produced by turbulent blood flow, a sign of carotid artery stenosis. Finally, to assess for peripheral vascular disease, auscultate for abdominal bruits at the aorta area, renal arteries, and femoral arteries.
You’ve just watched JoVE’s presentation on cardiac auscultation. The video reviewed important auscultation landmarks and illustrated how to perform the steps of this exam in a structured fashion.
Auscultation of the heart remains one of the fundamental skills for any clinician to master, and it provides vital diagnostic clues to many cardiac abnormalities. Therefore, learning the correct technique for auscultation is essential in order to be able to distinguish normal from pathological. As always, thanks for watching!
